Types of Chemical Bonds

There are two types of chemical bonds - Ionic and Covalent

Ionic Bond

The chemical bond formed by the transfer of electrons from one atom to another is known an an ionic bond. It is formed when one atom donates electrons and the other accepts electrons, so that both achieve the inert gas electron configuration. Ionic bonds are formed between metals and non-metals. The compounds containing ionic bonds are called ionic compounds. Ionic compounds are made up of ions. They are also called electrovalent compounds. Examples: Sodium chloride, potassium nitrate, copper sulphate, calcium oxide, sodium hydroxide, ammonium sulphate, magnesium chloride etc.

Covalent Bond

The chemical bond formed by the sharing of electrons between two atoms in known as a covalent bond. It is formed when both the reacting atoms need electrons to achieve the inert gas electron configuration. When a non-metal combines with another non-metal, a covalent bond is formed. It can also be formed between two atoms of the same non-metal. The shared electrons are counted with both the atom. The compounds containing covalent bonds are called covalent compounds. Examples: Methane (CH₄), ethane (C₂H₆), ethene (C₂H₄), ethyne (C₂H₂), water (H₂O), ammonia (NH₃), ethanol (C₂H₅OH), hydrogen chloride gas (HCl), carbon dioxide (CO₂), carbon tetrachloride (CCl₄), glucose (C₆H₁₂O₆), cane sugar (C₁₂H₂₂O₁₁), urea [CO(NH₂)₂], hydrogen gas (H₂), oxygen gas (O₂), chlorine gas (Cl₂), etc.

Covalent bond are of three types:

• Single Bond is formed by the sharing of one pair of electrons between two atoms, as in hydrogen molecule (H-H), hydrogen chloride molecule (H-Cl).
• Double Bond is formed by the sharing of two pairs of electrons between two atoms, as in oxygen molecule (O=O), carbon dioxide molecule (O=C=O), and ethene molecule (H₂C=CH₂).
• Triple Bond is formed by the sharing of three pairs of electrons between three atom, as in nitrogen (N=-N) molecule and ethyne (acetylene) molecule (H-C=-C-H).

Properties of Ionic Compounds

• Ionic compounds are usually crystalline solids.
• They have high melting and boiling points, i.e., they are non-volatile.
• They are usually soluble in water, but insoluble in organic solvents like alcohol, acetone, benzene, ether, etc.
• They conduct electricity when they are dissolved in water or melted.

Properties of Covalent Compounds

• Covalent compounds are usually liquids or gases. Only some of them are solids. Examples of covalent solids are Glucose, Urea, etc.
• They usually have low melting points and boiling points, i.e., they are volatile.
• They are usually insoluble in water (except glucose, sugar, urea, etc.), but soluble in organic solvents.
• They do not conduct electricity.